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Bulent Basaran (basaran@prelude.ece.cmu.edu) wrote this:
: 1) Is it possible to have a data member of a user class with a LEDA type?
: e.g.,
: class C1{
:     array<string> A(0, 10);  // an array of strings
: }; 
: This is not a valid c++ statement, since data members can not be initialized.
: Is there a way to correctly implement this?

I'd say ...

  class C1 {
    array<string>       A;

    public:

    C1() : A(0,10) {}
    void test() { 
        cout << "low: " << A.low() << " high: " << A.high() << endl; }
  };

  C1 test;

  test.test();

-- 
Marco Nissen [http://www.mpi-sb.mpg.de/~marco]
*this posting was not sponsered by microsoft*

Bulent Basaran (basaran@prelude.ece.cmu.edu) wrote:

> Hi,
> I have two questions:

> 1) Is it possible to have a data member of a user class with a LEDA type?
> e.g.,
> class C1{
>     array<string> A(0, 10);  // an array of strings
> }; 
> This is not a valid c++ statement, since data members can not be initialized.
> Is there a way to correctly implement this?

When I remember correctly, you have to initalize the member *before* the
normal constructor. Try this:

class C1{
    array<string> A;

    C1() : A(0,10);
	{ }
};


> 2) Is it possible to derive from a LEDA type?
> e.g., 
> class C1: public d_array {
> ...
> }

It is at least possible.
A friend of mine tried to code something like that, but he had some problems
in manipulating the object he derived from. Just try it.

Greetings, Muzz

--
  ___  Frank Muzzulini     ua0y@rz.uni-karlsruhe.de     Muzz@irc
 <*,*>  ... until the colour of a man skin is of no more
 [`-']  significance than the colour of his eyes ...        Bob Marley (War)
 -"-"-

In article <449i92$ae6@nz12.rz.uni-karlsruhe.de>
ua0y@rzstud1.rz.uni-karlsruhe.de (Frank Muzzulini) writes:

[...] 
>> Bulent Basaran (basaran@prelude.ece.cmu.edu) wrote:
[...] 
>> > 2) Is it possible to derive from a LEDA type?
>> > e.g., 
>> > class C1: public d_array {
>> > ...
>> > }
>> 
>> It is at least possible.  A friend of mine tried to code something
>> like that, but he had some problems in manipulating the object he
>> derived from. Just try it.

C++ permits it, of course, but be very careful. Many LEDA classes have
been written without thinking about possible derivation.

For instance, the `graph' class is the base class for `GRAPH',
`ugraph' and `planar_map'. But a `ugraph' is a graph with its
`undirected' field set to true, thus the behaviour of the undirected
graph is (partly) implemented in the `graph' class. Thus, if you
derived from `graph', in order not to interfere with `ugraph', you
need to know that `graph' was written with `ugraph' in mind... Tricky.

It is one of the coding practice I regret in LEDA. I suppose it was
hardly avoidable.

>>   ___  Frank Muzzulini     ua0y@rz.uni-karlsruhe.de     Muzz@irc

						Olivier L'Heureux

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